The marathon is the ultimate challenge for any runner, and for some there comes that dark moment when the pain wins
For many, the moment of deepest despair comes as they turn their backs on the swanky seaside suburb of St Heliers. The aches and pains accrued over 32km of battling gravity and a relentless pavement are now impossible to ignore. Getting this far has required the body to burn through nearly all the carbohydrates stored in its system, so energy levels are tanking.
Hydration is also an issue. The signals being sent to the brain are almost all negative. A deep resolve is the only thing keeping many of the 3000-odd Auckland Marathon contestants driving forward.
Rounding the St Heliers hairpin to be greeted by a stiff headwind - the city's predominant westerly always seems to be blowing on race day - and the sight of the Sky Tower looking impossibly small for something that stands 328m can be too much to take. As far as they've come, the shrunken Sky Tower rams home how far they still have to go.
"It's this minute shape in the distance," says Beachlands teacher Alexcia Andrews, who is running the race for the fourth time.
"That would be the hardest part of the race. You're just absolutely drained and disheartened. It takes a bit to get your head back in the game. You see quite a bit of walking at that point. That last hour is just horrific.
"We've taken to putting our names on our T-shirts. People call out and it feels like you've got friends on the course."
An adjunct professor and performance physiologist at AUT who also leads the performance physiology team at High Performance Sport NZ, Paul Laursen has experienced the horror of the St Heliers U-turn.
"I've done it once and I'd agree, that was definitely a tough one for me. That is almost at the stage they talk about where you hit the wall.
"For the typical person who has a normal diet, that tends to be the spot where you run out of muscle glycogen stores. Your blood sugar level drops and you proceed to fatigue. It also tends to be the distance that a lot of athletes don't train up to."
Everyone has a marathon horror story that for some reason seems amusing after the passing of a safe period of time. For Laursen it was a colleague getting his pacing horribly wrong and paying the price.
"He went out at a cracking pace. He was pretty close to that three-hour barrier at the half way point. He wound up closer to four hours, stumbling and walking that last bit. There is a classic video of him going across the line in absolute agony."
For an Irish friend of Andrew's who travelled from Sydney for the race in 2012, the final drag back from St Heliers proved too much. She collapsed at the turnoff for the The Strand on Tamaki Drive.
Plenty don't get that far. Of the 3610 entrants in last year's event, only 2733 made it the full 42.195km. That means 887 hopefuls didn't finish - or didn't even start.
The event is not kind on the human body. Last year 140 competitors required treatment from St John paramedics for ailments ranging from breathing difficulties and severe dehydration to blisters and chafing. In 2012, a competitor had a heart attack, happily not fatal.
Pheidippides, the ancient Greek hero credited with running the first marathon, wasn't so fortunate. Legend has it that, having run the 40km from Marathon to Athens to announce a Greek victory in a battle with Persia, he keeled over and died.
Of course, Pheidippides had also run about 240km in the previous two days to request help from Sparta.
The moral of the story seems clear - be careful not to over-train.